Light-emitting device and method of manufacturing the same

ABSTRACT

A light-emitting device includes: a plurality of light-emitting elements arranged in an array on a base member; and a compound eye lens that comprises at least four Fresnel lenses disposed above the base member and facing the plurality of light-emitting elements. In a top plan view, a center of each of the plurality of light-emitting elements is offset from a lens center of the corresponding one of the Fresnel lenses of the compound eye lens in a direction toward a center of the compound eye lens. The plurality of light-emitting elements include at least two first light-emitting elements and at least two second light-emitting elements, wherein an emission color of the first light-emitting elements is different from an emission color of the second light-emitting elements.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/557,260, filed on Aug. 30, 2019, which claims priority toJapanese Patent Application No. 2018-162681, filed on Aug. 31, 2018, theentire contents of which are incorporated herein by reference in theirentireties.

BACKGROUND OF THE INVENTION

The present disclosure relates to a light-emitting device and a methodof manufacturing the same.

Known light-emitting devices used for a flash for camera, etc., includea plurality of light-emitting elements, and a plurality of lenses, eachcombined with a respective one of the plurality of the light-emittingelements (for example, see Japanese Patent Application Publication No.2016-224394).

SUMMARY

When the number of light-emitting elements in a light-emitting device isincreased so as to increase the output power, the size of a lens isincreased, which leads to increase in size of the light-emitting device.Therefore, in order to miniaturize the device without changing thenumber of light-emitting elements and the size of the lens, reduction inthe distance between the light-emitting elements is considered. However,reduction in the distance between the light-emitting elements may causeunevenness in the illuminance distribution. In particular, reduction inthe distance between the light-emitting elements that emit differentcolors may cause unevenness in emission color when the light-emittingelements are turned on at the same time.

Certain embodiments according to the present disclosure allow forobtaining a light-emitting device with small size in which unevenness inemission color is reduced, and a method of manufacturing thelight-emitting device.

According to one embodiment, a light-emitting device includes aplurality of light-emitting elements arranged in an array on a basemember; and a compound eye lens that has a plurality of lens partsdisposed above the base member and facing the plurality oflight-emitting elements. The plurality of light-emitting elements arearranged such that each of the plurality of light-emitting elementsfaces a corresponding one of the lens parts, and the center of each ofthe plurality of light-emitting elements is offset from a lens center ofthe corresponding one of the lens parts of the compound eye lens in adirection toward a center of the compound eye lens in a plan view. Theplurality of light-emitting elements include first light-emittingelements and second light-emitting elements that are alternatelyarranged, an emission color of the first light-emitting elements and anemission color of the second light-emitting elements different from eachother.

According to another embodiment, a light-emitting device includes aplurality of light-emitting elements provided in an array on a basemember; and a compound eye lens that has a plurality of lens partsdisposed above the base member and facing the plurality oflight-emitting elements. The plurality of light emitting elementsinclude: one light-emitting element having a center that faces a lenscenter of a lens portion of the plurality of lens portions that isdisposed at a center of the compound eye lens in a plan view, and otherlight-emitting elements, each of which faces a corresponding one of theplurality of lens parts and has a center offset from a lens center ofthe corresponding one of the plurality of lens parts of the compound eyelens in a direction toward the center of the compound eye lens in a planview, including first light-emitting elements and second light-emittingelements that are alternately arranged, an emission color of the firstlight-emitting elements and an emission color of the secondlight-emitting elements different from each other.

According to another embodiment, a method of manufacturing alight-emitting device includes arranging a plurality of light-emittingelements in an array on a base member; and securing a compound eye lenshaving a plurality of lens parts above the base member. In the step ofarranging light-emitting elements, the plurality of light-emittingelements are arranged such that each of the plurality of light-emittingelements faces a corresponding one of the plurality of lens parts andthe center of each of the plurality of light-emitting elements is offsetfrom a lens center of the corresponding one of the lens parts of thecompound eye lens in a direction toward a center of the compound eyelens. The plurality of light-emitting elements includes firstlight-emitting elements and second light-emitting elements that arealternately arranged, an emission color of the first light-emittingelements and an emission color of the second light-emitting elementsdifferent from each other.

According to certain embodiments of the present disclosure, it ispossible to obtain a light-emitting device of a small size in whichunevenness in emission color is reduced. According to certainembodiments of the present disclosure, it is possible to manufacture alight-emitting device of a small size in which unevenness in emissioncolor is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing a configuration of alight-emitting device according to a first embodiment.

FIG. 2 is a schematic sectional view taken along the line II-II in FIG.1.

FIG. 3 is a schematic sectional view showing an example of aconfiguration of a light source device shown in FIG. 2.

FIG. 4 is a flowchart showing a procedure of a method of manufacturingthe light-emitting device according to the first embodiment.

FIG. 5 is a schematic plan view showing a configuration of alight-emitting device according to a first comparative example.

FIG. 6 is a schematic plan view showing a configuration of alight-emitting device according to a second comparative example.

FIG. 7 is a schematic sectional view showing the configuration of thelight-emitting device according to the first comparative example.

FIG. 8 is a schematic sectional view showing the configuration of thelight-emitting device according to the first embodiment.

FIG. 9 schematically shows luminance distributions obtained by thelight-emitting device according to the first comparative example.

FIG. 10 shows schematic luminance distributions irradiated by thelight-emitting device according to the second comparative example.

FIG. 11 shows schematic irradiation distributions irradiated by thelight-emitting device according to the first embodiment.

FIG. 12 is a schematic plan view showing a configuration of alight-emitting device according to a second embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments of a light-emitting device according to thepresent invention are described.

The drawings referred to in the description below schematicallyillustrate certain embodiments of the present invention, and scale,distance, positional relationship and the like of members may beexaggerated, or illustration of a part of a member may be omitted. Also,the scale of a member and distance between members may not be consistentbetween the plan view and the sectional view. Further, in thedescription below, the same designations or reference numerals indicatethe same members or members made of the same materials, and a detaileddescription thereof is omitted as appropriate.

In a light-emitting device according to certain embodiments of thepresent invention, the terms “upper,” “lower,” “left” and “right” areinterchangeable depending on the situation. In the presentspecification, the terms such as “upper” and “lower” are used toindicate a relative position between components in the drawings referredto for an explanation, and are not intended to indicate an absoluteposition unless otherwise specified.

First Embodiment Configuration of Light-Emitting Device

A configuration of a light-emitting device according to a firstembodiment of the present invention is described with reference to FIGS.1 to 3. FIG. 1 is a schematic plan view showing the configuration of thelight-emitting device according to the first embodiment. FIG. 2 is aschematic sectional view taken along the line II-II in FIG. 1. FIG. 3 isa schematic sectional view showing an example of a configuration of alight source device shown in FIG. 2.

A light-emitting device 100 constitutes, for example, a flash module fora camera. The light-emitting device 100 is incorporated in a housing 4of a smartphone, a tablet terminal or the like. The housing 4 includes amain body 41 made of, for example, stainless steel, and a cover glass 42covering the light-emitting device 100 incorporated in the housing 4.The cover glass 42 is disposed in a through hole 43 of the main body 41.FIG. 1 shows a portion of the light-emitting device that can be seenthrough the cover glass 42 attached to the through hole 43 of the mainbody 41.

The light-emitting device 100 includes a light source device 10 having aplurality of light-emitting elements 1 disposed in an array on a basemember 5, and a compound eye lens 30. The plurality of light-emittingelements 1 include first light-emitting elements 1A and secondlight-emitting elements 1B having different emission colors. The firstlight-emitting elements 1A and the second light-emitting elements 1B arealternately arranged in an array on the base member 5. When describedwithout identifying as the first light-emitting element 1A or the secondlight-emitting element 1B, each of the plurality of light-emittingelements 1 is referred to as a light-emitting element 1. The compoundeye lens 30 is disposed above the base member 5 such that a lens holder31 is disposed between the compound eye lens 30 and the base member 5,and the compound eye lens 30 has lens parts each facing a respective oneof the light-emitting elements 1. As shown in FIG. 1, in a plan view,the plurality of light-emitting elements 1 are arranged such that thecenter of each of the plurality of light-emitting elements, each facinga corresponding one of the lens part of the compound eye lens 30, islocated offset from the lens center of the corresponding lens portion ofthe compound eye lens 30 in a direction toward the center of thecompound eye lens 30.

The light source device 10 further includes the base member 5 andconductive wirings 6 as shown in FIG. 3. The base member 5 is acomponent supporting the light-emitting elements 1 and the like, and acommon package substrate for a light-emitting device can be used for thebase member 5. For example, a ceramic substrate such as an AlNsubstrate, a metal substrate such as an Al substrate, or a resinsubstrate such as a glass epoxy substrate can be used for the basemember 5.

The conductive wirings 6 are disposed, for example, on an upper surfaceof the base member 5. The conductive wirings 6 are wirings for supplyingpower to the light-emitting elements 1 from the outside, and arepatterned in a predetermined shape on the base member 5. Each conductivewiring 6 includes, for example, a wiring portion penetrating the basemember 5 and another wiring portion exposed at the lower surface of thebase member 5, with which each conductive wiring 6 is connected to anexternal power supply. For the conductive wirings 6, wirings commonlyused for package substrates of light-emitting devices can be used. Thewirings are preferably made of a metal, for example, a single metal suchas Ag, Al, Ni, Rh, Au, Cu, Ti, Pt, Pd, Mo, Cr, and W, or an alloycontaining one or more of these metals. More preferably, the wirings aremade of a single metal having a high reflectivity such as Ag, Al, Pt,and Rh, or an alloy containing one or more of these metals.

The wiring electrically connected to the negative electrode of each ofthe light-emitting elements 1 and exposed from the lower surface of thebase member 5 and the wiring electrically connected to the positiveelectrode of the light-emitting element 1 and exposed from the lowersurface of the base member 5 are insulated by an insulating layer 7.

The light-emitting device 100 includes the plurality of light-emittingelements 1. Each light-emitting element 1 includes a light-emittingdiode, a wavelength conversion member disposed on the light-emittingdiode, and a protective member covering lateral surfaces of thelight-emitting diode and lateral surfaces of the wavelength conversionmember. Each light-emitting element 1 is mounted on the upper surface ofthe base member 5 so as to be electrically connected to the conductivewiring 6. The plurality of light-emitting elements 1 are arranged in aplan view. Of the plurality of light-emitting elements 1, the firstlight-emitting elements 1A emit white light, and the secondlight-emitting elements 1B emit light having a more red component thanthat of light emitted by the first light-emitting elements 1A. Thedescription below is on the assumption that the second light-emittingelements 1B emit amber light.

The term “amber” as used herein refers to a chromaticity range includingthe longer-wavelength range of yellow and the shorter-wavelength rangeof yellowish red in JIS Z 8110, and a chromaticity range between theyellow range and the short-wavelength range of yellow red in JIS Z 9101,which defines safety colors. For example, the “amber” as used hereinrefers to a color having a dominant wavelength in a range of 580 nm to600 nm.

The light-emitting diode includes a semiconductor layer 22 on a lighttransmissive substrate 21 such as a sapphire substrate. Thesemiconductor layer 22 includes an n-side semiconductor layer, an activeregion, and a p-side semiconductor layer in order from the substrate 21side. For a light-emitting diode 2 configured to ultraviolet light orblue-to-green visible light, for example, a GaN-based or InGaN-basednitride semiconductor expressed as In_(X)Al_(Y)Ga_(1-X-Y)N (0≤X≤1,0≤Y≤1, X+Y≤1) can be used. The substrate 21 may be removed. A plan viewshape of the light-emitting diode 2 is, for example, a rectangularshape, but may be a circle, an ellipse, a triangle, or a polygon such asa hexagon.

The light-emitting diode 2 that has positive and negative electrodes 23on an identical surface is preferable, and thus is capable of beingflip-chip mounted on or above the base member 5. In the presentembodiment, the positive and negative electrodes 23 of thelight-emitting diode 2 are respectively electrically connected to theconductive wirings 6 of the base member 5 via a bonding member 9 such asa bump, a conductive paste, or solder.

Each first light-emitting element 1A includes a blue light-emittingdiode 2, a first wavelength conversion member 3A provided on the bluelight-emitting diode 2, and a protective member 8 covering lateralsurfaces of the blue light-emitting diode 2 and lateral surfaces of thefirst wavelength conversion member 3A.

The first wavelength conversion member 3A is disposed covering an uppersurface of the light-emitting diode 2 in a top view. The firstwavelength conversion member 3A is a plate-like light transmissivemember having a substantially rectangular shape in a plan view, andcontains a yellow phosphor.

Examples of the yellow phosphor contained in the first wavelengthconversion member 3A include Tb_(2.95)Ce_(0.05)Al₅O₁₂,Y_(2.90)Ce_(0.05)Tb_(0.05)Al₅O₁₂, Y_(2.94)Ce_(0.05)Pr_(0.01)Al₅O₁₂, andY_(2.90)Ce_(0.05)Pr_(0.05)Al₅O₁₂, in addition to an yttrium aluminumoxide phosphor (YAG phosphor).

A light transmissive resin, glass, or the like can be used for the lighttransmissive member. Examples of the light transmissive resin includethermosetting resins such as silicone resin, silicone modified resin,epoxy resin, and phenol resin, and thermoplastic resins such aspolycarbonate resin, acrylic resin, methyl pentene resin, andpolynorbornene resin. In particular, silicone resins having goodlight-resisting properties and good heat-resisting properties aresuitable. The transmittance of the light transmissive member withrespect to light emitted from the light-emitting diode is preferably 70%or greater, more preferably 80% or greater.

Each second light-emitting element 1B includes a blue light-emittingdiode 2, a second wavelength conversion member 3B provided on the bluelight-emitting diode 2, and a protective member 8 covering lateralsurfaces of the blue light-emitting diode 2 and lateral surfaces of thesecond wavelength conversion member 3B.

The second wavelength conversion member 3B is disposed covering an uppersurface of the blue light-emitting diode 2 in a top view. The secondwavelength conversion member 3B is a light transmissive member having aplate-like shape with a substantially rectangular shape in a plan view.The second wavelength conversion member 3B includes a red phosphor thatconverts blue light emitted from the blue light-emitting diode 2 intoamber light.

Examples of the red phosphor contained in the second wavelengthconversion member 3B preferably include, for example, a nitride-basedphosphor such as (Sr_(0.97)Eu_(0.03))₂Si₅N₈,(Ca_(0.985)Eu_(0.015))₂Si₅N₈, and (Sr_(0.679)Ca_(0.291)Eu_(0.03))₂Si₅N₈,in addition to sialon phosphor (SiAlON phosphor). On the other hand, theresin materials, glass, and the like described above can be used for thelight transmissive member containing the red phosphor.

The first light-emitting elements 1A and the second light-emittingelements 1B are arranged electrically independent of each other. Morespecifically, the light source device 10 is configured such that thefirst light-emitting elements 1A and the second light-emitting elements1B can be individually controlled, so that the intensity of lightextracted from the first light-emitting elements 1A and the secondlight-emitting elements 1B can be controlled in a desired manner. Thefirst light-emitting elements 1A and the second light-emitting elements1B are electrically independent from each other, but may be on the samecircuit 1.

Each first light-emitting element 1A and each second light-emittingelement 1B respectively includes the protective members 8. Eachprotective member 8 protects the lateral surfaces of the light-emittingdiode and the lateral surfaces of the wavelength conversion member. Theprotective member 8 directly or indirectly covers the lateral surfacesof the light-emitting diode and the lateral surfaces of the wavelengthconversion member. In the first light-emitting elements 1A and thesecond light-emitting elements 1B, and upper surface of each of thefirst wavelength conversion members 3A and an upper surface of each ofthe second wavelength conversion members 3B are exposed from theprotective members 8, and constitute light-emitting surfaces (i.e., mainlight extraction surfaces) of the first light-emitting elements 1A andthe second light-emitting elements 1B, respectively. The protectivemembers 8 are preferably made of a material having a high lightreflectance. For example, a resin material containing a light reflectivesubstance can be used for the protective member 8. Examples of the lightreflective substance include titanium oxide, silicon oxide, zirconiumoxide, potassium titanate, aluminum oxide, aluminum nitride, boronnitride, zinc oxide, and mullite. A resin material whose main componentis a thermosetting resin such as epoxy resin, silicone resin, siliconemodified resin, or phenol resin is preferable for a base material of theprotective member 8. The protective member 8, can also be composed of amaterial transmissive to visible light may be as needed.

The compound eye lens 30 is provided above the light source device 10such that the lens holder 31 is disposed between the compound eye lens30 and the light source device 10. The lens holder 31 is disposed on thelight source device 10 via an adhesive member such as resin. Thecompound eye lens 30 disposed covering the entirety of thelight-emitting surface of each of the first light-emitting elements 1Aand the entirety of the light-emitting surface of each of the secondlight-emitting elements 1B in a plan view, as shown in FIG. 1. In a planview, the compound eye lens 30 may have, for example, a rectangular, acircular, or an elliptic external shape. The compound eye lens 30 can bemanufactured using a known method and a known material in the art.Examples of a material of the compound eye lens 30 include a resin and aglass. The material of the compound eye lens may contain a lightdiffusing material and the like.

Each of the lens parts of the compound eye lens 30 forms a Fresnel lens.The Fresnel lens includes an uneven first surface facing the lightsource device 10 and a flat second surface, such that a light beamemitted from the light source device 10 is incident on the first surfaceand is emitted from the second surface. The lens part having a Fresnellens structure allows for reducing a thickness of the lens part, so thata length of an entirety of the light-emitting device can be reduced in alight extraction direction. Further, reduction in thickness of the lenspart allows an air layer to be easily present between the compound eyelens 30 and the light source device 10. With the air layer, spread oflight emitted from the light source device 10 can be adjusted. Thecompound eye lens 30 is provided with the lens holder 31 at an outerperiphery of the compound eye lens 30. The lens holder 31 is secured onthe compound eye lens 30 above the light source device 10 such that theair layer is interposed between the upper surface of the light-emittingelement 1 and the light incident surface of the compound eye lens 30.

In an example shown in FIG. 1, the compound eye lens 30 includes fourFresnel lenses. Under the compound eye lens 30, the two firstlight-emitting elements 1A and the two second light-emitting elements 1Bare provided in an array. The four Fresnel lenses are arranged in tworows and two columns. As in the four Fresnel lenses, the two firstlight-emitting elements 1A and the two second light-emitting elements 1Bare arranged in two rows and two columns as an entirety.

More specifically, in a first row of the two rows, the firstlight-emitting element 1A and the second light-emitting element 1B arearranged adjacent to each other in this order. In the second row of thetwo rows, the second light-emitting element 1B and the firstlight-emitting element 1A are arranged adjacent to each other in thisorder. That is to say, the two first light-emitting elements 1A and thetwo second light-emitting elements 1B are provided in the array of tworows and two columns so as to form a substantially rectangular shape ina plan view as a whole, and the two first light-emitting elements 1A andthe two second light-emitting elements 1B are respectively arranged atcorners of diagonals of the rectangular shape.

In the description below, a light-emitting element located at the m-throw and the n-th column of the plurality of light-emitting elementsarranged in rows and columns is referred to as a light-emitting element(m, n). The light-emitting device 100 includes the first light-emittingelement 1A (1, 1), the second light-emitting element 1B (1, 2), thesecond light-emitting element 1B (2, 1), and the first light-emittingelement 1A (2, 2).

In the example shown in FIG. 1, it can also be considered that the firstlight-emitting element 1A, the second light-emitting element 1B, thefirst light-emitting element 1A, and the second light-emitting element1B are arranged clockwise.

Alternatively, the light-emitting device may include a secondlight-emitting element 1B (1, 1), a first light-emitting element 1A (1,2), a first light-emitting element 1A (2, 1), and a secondlight-emitting element 1B (2, 2). Also in this case, the firstlight-emitting element 1A and the second light-emitting element 1B arearranged adjacent to each other alternately in each row.

In the example shown in FIG. 1, in a plan view, the lens center of eachof the Fresnel lenses of the compound eye lens 30 and the center of acorresponding one of the first light-emitting elements 1A or the secondlight-emitting elements 1B that faces the respective Fresnel lens arelocated offset from each other. In the example shown in FIG. 1, thecenters of the first light-emitting elements 1A and the centers of thesecond light-emitting elements 1B are offset toward the center of thecompound eye lens 30. An offset distance is preferably 100 μm or less,which allows for reducing unevenness in illuminance distribution asdescribed below. The expression “offset distance” as used herein refersto a distance at which the center of each of the light-emitting elements1 is offset from the lens center of a corresponding one of the lensparts facing the respective light-emitting element toward the center ofthe compound eye lens 30, and indicates a distance D1 in a plan viewbetween the center of each of the light-emitting elements 1 and the lenscenter of a corresponding one of the lens parts facing thelight-emitting element.

In the example shown in FIG. 1, the distance D1 between the center ofeach light-emitting element 1 and the lens center of a corresponding oneof the lens parts facing the light-emitting element is preferably 0 mmto 0.1 mm in a plan view. Further, a distance D2 between the center ofthe first light-emitting element 1A and the center of the secondlight-emitting element 1B is preferably in arrange of 1.2 mm to 1.3 mm.

Operation of Light-Emitting Device

When the light-emitting device 100 having a structure as described aboveis connected to an external power source, the light-emitting element 1is supplied with current and emits light. The light is extracted outsidefrom the upper surface of the light-emitting element 1 through thecompound eye lens 30. The light propagating in a lateral direction ofthe light-emitting element 1 is reflected at the protective member 8,and is extracted outside from the upper surface of the light-emittingelement 1. Further, in the light-emitting device 100, the firstlight-emitting elements 1A and the second light-emitting elements 1B canbe individually controlled. Accordingly, when the light-emitting device100 is used for a flash module for a camera, a desired emission coloraccording to an object to be photographed can be obtained. For example,when only the first light-emitting elements 1A are allowed to emitlight, white light is emitted, and when only the second light-emittingelements 1B are allowed to emit light, amber light is emitted. Alternatearrangement of the first light-emitting elements 1A and the secondlight-emitting elements 1B allows for reducing unevenness in illuminancedistribution of each emission color. When the first light-emittingelements 1A and the second light-emitting elements 1B are allowed toemit light simultaneously, both the white light and the amber light areemitted and diffused by the compound eye lens 30. With the firstlight-emitting elements 1A and the second light-emitting elements 1Bthat are alternately arranged such that the center of each of the firstlight-emitting elements 1A and the center of each of the secondlight-emitting elements 1B are offset from respective lens centers ofrespective lens parts of the compound eye lens 30 toward the center ofthe compound eye lens 30 as described below, unevenness in illuminancedistribution and emission unevenness in emission color can be reduced.Thus, the light-emitting device 100 can irradiate light of a uniformemission color to an irradiation region, even when irradiating light ofadjusted color obtained from the first light-emitting elements 1A andthe second light-emitting elements 1B.

Method of Manufacturing Light-Emitting Device

A method of manufacturing the light-emitting device 100 shown in FIG. 1will be described. As shown in FIG. 4, the method of manufacturing thelight-emitting device 100 includes providing light-emitting elements(S1), arranging light-emitting elements (S2), and fixing a lens (S3),which are performed in this order.

In the step S1 of providing light-emitting elements, the plurality oflight-emitting elements 1 are provided.

In this step, the two first light-emitting elements 1A and the twosecond light-emitting elements 1B are provided. Light-emitting elementsthat have already been manufactured may be used for the firstlight-emitting elements 1A and the second light-emitting elements 1B, orthe first light-emitting elements 1A and the second light-emittingelements 1B may be manufactured as a part of the method. Whenmanufacturing the first light-emitting elements 1A, for example, asapphire substrate is used for the light transmissive substrate 21, andthe semiconductor layer 22 made of nitride semiconductors containing anactive region made of InGaN-based semiconductor is formed using metalorganic chemical vapor deposition (MOCVD) method. Further, the positiveand negative electrodes 23 made of, for example, an Au/Ti alloy aredisposed on the semiconductor layer 22. Accordingly, a chip of the bluelight-emitting diode 2 can be formed. Subsequently, a resin layercontaining the yellow phosphor is applied on a surface of the substrate21 of the blue light-emitting diode 2 using, for example, screenprinting method, so that the first wavelength conversion member 3A isformed. Furthermore, the lateral surfaces of the first wavelengthconversion member 3A are covered with the protective member 8. The uppersurface of the first wavelength conversion member 3A is exposed from theprotective member 8, so that the first light-emitting element 1A inwhich the upper surface of the first wavelength conversion member 3Aserves as the main light extraction surface can be obtained. Whenmanufacturing the second light-emitting elements 1B, the secondlight-emitting elements 1B can be manufactured in a manner as inmanufacturing of the first light-emitting elements 1A except that aresin layer contains the red phosphor.

In the step S2 of arranging light-emitting elements, the plurality oflight-emitting elements 1 are arranged in the array at the base member5. In this step, the two provided first light-emitting elements 1A andthe two provided second light-emitting elements 1B are alternatelyarranged at the base member 5. Each of the positive and negativeelectrodes 23 of each light-emitting element 1 and a corresponding oneof the conductive wirings 6 on the base member 5 are connected via thebonding members 9 (for example, solder) such that each of thelight-emitting elements 1 faces a corresponding one of the lens parts ofthe compound eye lens 30 and the center of each of the plurality oflight-emitting elements 1 is located offset from the lens center of thecorresponding lens part toward the center of the compound eye lens 30,and.

In the step S3 of securing a lens, the compound eye lens 30 is fixedabove the base member 5 of the light source device 10. In this step, thecompound eye lens 30, in which the lens parts each including thesubstantially circular Fresnel lens are integrated, is disposed abovethe light source device 10. The lens holder 31 is secured on the basemember 5 so that the upper surfaces of the light source device 10 andthe light incident surface of the compound eye lens 30 are spaced apartfrom each other. The lens holder 31 is disposed on the base member 5 viathe resin material and heated, so that the base member 5 and the lensholder 31 are bonded. Through the steps described above, thelight-emitting device 100 shown in FIG. 1 can be manufactured.

Alternatively, instead of the step S1 of providing light-emittingelements and the step S2 of arranging light-emitting elements,plate-shaped first wavelength conversion members 3A and plate-shapedsecond wavelength conversion members 3B may be alternately bonded ontothe substrates 21 of respective blue light-emitting diodes 2 that havebeen arranged on the base member 5.

Next, effects of the light-emitting device 100 will be described.Light-emitting devices according to comparative examples are shown inFIG. 5 and FIG. 6, in each of which the first light-emitting elements 1Aand the second light-emitting elements 1B are not alternately arrangedand the number of light-emitting elements 1 and the size of the compoundeye lens 30 are the same as those in the light-emitting device 100. FIG.5 is a plan view schematically showing a configuration of thelight-emitting device according to a first comparative example. FIG. 6is a plan view schematically showing a configuration of thelight-emitting device according to a second comparative example. In eachof FIG. 5 and FIG. 6, a housing 4 is not illustrated, and a portion ofthe light-emitting device that can be seen through a cover glass 42attached to a through hole 43 of a main body 41 is illustrated.

As shown in FIG. 5, a light-emitting device 200 according to the firstcomparative example includes two first light-emitting elements 1Adisposed in a first row, and two second light-emitting elements 1Bdisposed in a second row. When a light-emitting element 1 located in them-th row and the n-th column is referred to as a “light-emitting element1 (m, n)”, the light-emitting device 200 includes the firstlight-emitting element 1A (1, 1), the first light-emitting element 1A(1, 2), the second light-emitting element 1B (2, 1), and the secondlight-emitting element 1B (2, 2). In the light-emitting device 200according to the first comparative example, each of Fresnel lenses of acompound eye lens 30 faces a corresponding one of the first and secondlight-emitting elements 1A and 1B, and, in a plan view, a lens center ofeach Fresnel lens of the compound eye lens 30 and a center of thecorresponding one of the first and second light-emitting elements 1A and1B substantially correspond to each other.

On the other hand, the intervals between the light-emitting elements 1is smaller in the light-emitting device 100 than in the light-emittingdevice 200. That is, the distance D2 between the centers of adjacentlight-emitting elements shown in FIG. 1 is shorter than a distance D3between the centers of adjacent light-emitting elements shown in FIG. 5.Accordingly, in the light-emitting device 100, reduction in intervalsbetween the light-emitting elements 1 allows for obtaining an area thatcan be effectively used for, for example, a mounting area for a memberother than the light-emitting elements such as a protection device or asensor. Therefore, it is not necessary to add areas for mounting themembers other than the light-emitting elements, so that the entire sizeof the light-emitting device can be reduced.

When the light-emitting device 200 according to the first comparativeexample is incorporated in the housing 4, as shown in FIG. 7, forexample, a light beam L1, which is a portion of light emitted from thefirst light-emitting elements 1A, is absorbed by the main body 41 of thehousing 4, and may not be extracted outside.

On the other hand, when the light-emitting device 100 is incorporated inthe housing 4, as shown in FIG. 8, for example, a light beam L2, whichis a portion of light emitted from the first light-emitting elements 1A,is not absorbed by the main body 41 of the housing 4, and can beextracted outside. Therefore, light absorbed by the main body 41 of thehousing 4 can be reduced more in the light-emitting device 100 than inthe light-emitting device 200. Accordingly, in the light-emitting device100, utilization ratio of light emitted from the light-emitting elements1 can be improved. In the description above, the light beam L2 and thelight beam L1 are assumed to be emitted at a same angle from a sameposition on the first light-emitting elements 1A.

As shown in FIG. 6, a light-emitting device 300 according to the secondcomparative example includes, as in the light-emitting device 200, afirst light-emitting element 1A (1, 1), a first light-emitting element1A (1, 2), a second light-emitting element 1B (2, 1), and a secondlight-emitting element 1B (2, 2). In the light-emitting device 300, asin the light-emitting device 100, each of the Fresnel lenses of acompound eye lens 30 faces a corresponding one of the firstlight-emitting elements 1A or a corresponding one of the secondlight-emitting elements 1B, and in a plan view, a lens center of eachFresnel lens of a compound eye lens 30 is offset from a center of thecorresponding one of the first light-emitting elements 1A or a center ofthe corresponding one of the second light-emitting elements 1B.Therefore, light absorbed by the main body 41 of the housing 4 can bereduced more in the light-emitting device 300 than in the light-emittingdevice 200.

FIGS. 9 to 11 respectively show schematic irradiation distributionsirradiated by the light-emitting devices 200, 300, and 100. FIG. 9 showsschematic irradiation distributions irradiated by the light-emittingdevice according to the first comparative example. FIG. 10 showsschematic irradiation distributions irradiated by the light-emittingdevice according to the second comparative example. FIG. 11 showsschematic irradiation distributions irradiated by the light-emittingdevice according to the first embodiment. Note that rectangular framesin FIGS. 9 to 11 indicate an angle of view of a camera (i.e., regionscaptured by a camera), in which a positive direction of x-axis isopposite to those in FIGS. 1, 5 and 6. Each of FIGS. 9 to 11 shows, inorder from left to right, illuminance distribution when only the firstlight-emitting elements 1A emit light, illuminance distribution whenonly the second light-emitting elements 1B emit light, and illuminancedistribution when the first light-emitting elements 1A and the secondlight-emitting elements 1B collectively emit light. Symbols “W” “A” and“M” respectively denote the illuminance distributions of white light,amber light, and mixed-color light in which white light and amber lightare mixed.

As shown in FIG. 9, in the light-emitting device 200 according to thefirst comparative example, the illuminance distributions W, A, and M areuniform.

However, when the light-emitting device 200 according to the firstcomparative example is incorporated in the housing 4, light absorbed bythe main body 41 of the housing 4 may not be extracted outside asdescribed above, so that a narrower region in the angle of view of thecamera can be irradiated as compared to the light-emitting deviceaccording to the first embodiment.

In the light-emitting device 300 according to the second comparativeexample, center of each of the light-emitting elements is offset fromthe lens center of a corresponding lens part.

With this arrangement, light emitted from the first light-emittingelement 1A (1, 1) and passing through a corresponding lens part of thecompound eye lens 30 shifts in a positive y-axis direction, lightemitted from the first light-emitting element 1A (1, 2) and passingthrough a corresponding lens part of the compound eye lens 30 shifts ina positive y-axis direction, light emitted from the secondlight-emitting element 1B (2, 1) and passing through a correspondinglens part of the compound eye lens 30 shifts in a negative y-axisdirection, and light emitted from the second light-emitting element 1B(2, 2) and passing through the compound eye lens 30 shifts in a negativey-axis direction.

That is, light emitted from the first light-emitting elements 1A (1, 1)and 1A (1, 2) and passing through respective corresponding lens parts ofthe compound eye lens 30 shift in the same direction, which may likelyresult in uneven distribution of illuminance.

Also, light emitted from the second light-emitting elements 1B (2, 1)and 1B (2, 2) and passing through respective corresponding lens parts ofthe compound eye lens 30 shift in the same direction, which may likelyresult in uneven distribution of illuminance.

Accordingly, in the light-emitting device 300, when light is emittedfrom only the first light-emitting elements 1A, as shown in the left ofFIG. 10, the illuminance distribution W is uneven in the positive y-axisdirection in the angle of view of the camera. When light is emitted fromonly the second light-emitting elements 1B, as shown in the middle ofFIG. 10, the illuminance distribution A is uneven in the negative y-axisdirection in the angle of view of the camera. When light is emittedcollectively from the first light-emitting elements 1A and the secondlight-emitting elements 1B, as shown in the right of FIG. 10, theilluminance distribution M is not uneven in the angle of view of thecamera, and is distributed such that a shift in a positive y-axisdirection and a shift in a negative y-axis direction are integrated.Meanwhile, a white area and an amber area are generated near outerperiphery of the mixed-color area in the positive y-axis direction andouter periphery of the mixed-color area the negative y-axis direction,respectively, so that unevenness in emission color occurs.

On the other hand, also in the light-emitting device 100, the center ofeach of the light-emitting elements is offset from the lens center of acorresponding lens part.

With this arrangement, light emitted from the first light-emittingelement 1A (1, 1) and passing through a corresponding lens part of thecompound eye lens 30 shifts in a positive y-axis direction, lightemitted from the first light-emitting element 1B (1, 2) and passingthrough a corresponding lens part of the compound eye lens 30 shifts ina positive y-axis direction, light emitted from the secondlight-emitting element 1B (2, 1) and passing through a correspondinglens part of the compound eye lens 30 shifts in a y-axis negativedirection, and light emitted from the first light-emitting element 1A(2, 2) and passing through a corresponding lens part of the compound eyelens 30 shifts in a y-axis negative direction.

That is, light emitted from the first light-emitting elements 1A (1, 1)and 1A (2, 2) and passing through respective corresponding lens parts ofthe compound eye lens 30 shift in opposite directions, which allows forreducing unevenness in distribution of illuminance.

Also, light emitted from the second light-emitting elements 1B (1, 2)and 1B (2, 1) and passing through respective corresponding lens parts ofthe compound eye lens 30 shift in opposite directions, which allows forreducing unevenness in distribution of illuminance.

Accordingly, in the light-emitting device 100, as shown in FIG. 11, eachof illuminance distributions W, A, and M is not uneven, and isdistributed such that a shift in a positive y-axis direction and a shiftin a negative y-axis direction are integrated. Further, emission colorof the illuminance distribution M can be uniform.

Second Embodiment

FIG. 12 is a plan view schematically showing a configuration of alight-emitting device according to a second embodiment. As shown in FIG.12, a light-emitting device 100C according to the second embodimentincludes a different number of light-emitting elements and a differentshape of compound eye lens from those of the light-emitting device 100according to the first embodiment. Hereinafter, the same referencenumerals indicate the same or similar components as those of thelight-emitting device 100 shown in FIG. 1, and duplicative descriptionthereof will be omitted. In FIG. 12, illustration of a housing 4 isomitted, and a portion of the light-emitting device that can be seenthrough a cover glass 42 attached to a through hole 43 of a main body 41is shown.

The light-emitting device 100C includes a light source device 10including a plurality of light-emitting elements 1 arranged in an arrayon a base member 5 (see FIG. 2), and a compound eye lens 30C. Thecompound eye lens 30C is disposed above the base member 5 such that alens holder 31 disposed between the compound eye lens 30C and the basemember 5 (see FIG. 2), and includes a plurality of lens parts eachfacing a corresponding one of the light-emitting elements 1. As shown inFIG. 12, in a plan view, one of the plurality of light-emitting elements1 is disposed such that the center of the one light-emitting elementfaces a lens center of the lens part disposed at a center of thecompound eye lens 30C. Also, the other light-emitting elements of theplurality of light-emitting elements 1 are disposed such that, in a planview, the center of each of the other light-emitting elements is offsetfrom a lens center of a corresponding lens part of the compound eye lens30C in a direction toward the center of the compound eye lens 30C.Further, the other light-emitting elements of the plurality oflight-emitting elements 1 include first light-emitting elements 1A andsecond light-emitting elements 1B having different emission colors andalternately arranged adjacent to each other.

The light-emitting device 100C includes the plurality of light-emittingelements 1. Of the plurality of light-emitting elements 1, firstlight-emitting elements 1A emit white light, and second light-emittingelements 1B emit amber light, which has a more red component than thatof light emitted from the first light-emitting elements 1A. Thelight-emitting element 1 that faces the lens part disposed at the centerof the compound eye lens 30C in a plan view is the first light-emittingelement 1A.

The light-emitting device 100C according to the present embodimentincludes the first light-emitting element 1A (1, 1), the secondlight-emitting element 1B (1, 2), the second light-emitting element 1B(2, 1), the first light-emitting element 1A (2, 2), and the firstlight-emitting element 1A at the center of the plurality oflight-emitting elements 1. With this arrangement, as in thelight-emitting device 100, the light-emitting device 100C can have asmall size, and unevenness in emission color of the light-emittingdevice 100C can be reduced. Also, with the first light-emitting element1A disposed at the center and emitting white light, output of thelight-emitting device 100C can be effectively increased. A method ofmanufacturing the light-emitting device 100C is the same as the methoddescribed above, and will not be described in detail.

While the light-emitting devices according to certain embodiments of thepresent invention has been described above, the scope of the presentinvention is not limited to the descriptions above and should be broadlyunderstood on the basis of the claims. The scope of the presentinvention also includes various modifications based on thesedescriptions.

What is claimed is:
 1. A light-emitting device comprising: a pluralityof light-emitting elements arranged in an array on a base member; and acompound eye lens that comprises at least four Fresnel lenses disposedabove the base member and facing the plurality of light-emittingelements; wherein: in a top plan view, a center of each of the pluralityof light-emitting elements is offset from a lens center of thecorresponding one of the Fresnel lenses of the compound eye lens in adirection toward a center of the compound eye lens; and the plurality oflight-emitting elements include at least two first light-emittingelements and at least two second light-emitting elements, wherein anemission color of the first light-emitting elements is different from anemission color of the second light-emitting elements.
 2. Thelight-emitting device according to claim 1, wherein: each Fresnel lenscomprises an uneven first surface that faces a respective one of thelight-emitting elements.
 3. The light-emitting device according to claim2, wherein: the uneven first surface of each Fresnel lens comprises aplurality of protrusions, at least some of which have a surface that, ina side sectional view, extends diagonally toward the respective one ofthe light-emitting elements.
 4. The light-emitting device according toclaim 1, wherein: the direction toward the center of the compound eyelens in the top plan view, in which the center of each of the pluralityof light-emitting elements is offset from the lens center of thecorresponding one of the Fresnel lenses of the compound eye lens, is adirection that is diagonal with respect to lines connecting the lenscenters of adjacent Fresnel lenses.
 5. The light-emitting deviceaccording to claim 1, wherein: the light-emitting device includesexactly two of the first light-emitting elements, and exactly two of thesecond light-emitting elements, which are arranged in two rows and twocolumns; and the compound eye lens includes exactly four Fresnel lensesthat are arranged in two rows and two columns and that are rotationallysymmetric about the center of the Fresnel lens.
 6. The light-emittingdevice according to claim 1, wherein a red component of light emittedfrom the second light-emitting elements is greater than a red componentof light emitted from the first light-emitting elements.
 7. Thelight-emitting device according to claim 1, wherein a distance betweenthe center of one of the first light-emitting elements and the center ofan adjacent one of the second light-emitting elements in the plan viewis in a range of 1.2 mm to 1.3 mm.
 8. The light-emitting deviceaccording to claim 1, wherein an offset distance between the lens centerof each of the Fresnel lenses of the compound eye lens and the center ofeach corresponding first light-emitting element and each secondlight-emitting element is 100 μm or less in the plan view.
 9. Thelight-emitting device according to claim 1, wherein: each of the firstlight-emitting elements comprises: a first blue light-emitting diode,and a first wavelength conversion member disposed on the first bluelight-emitting diode and including a yellow phosphor, and each of thesecond light-emitting elements comprises: a second blue light-emittingdiode, and a second wavelength conversion member disposed on the secondblue light-emitting diode and including a red phosphor.
 10. Thelight-emitting device according to claim 1, wherein the firstlight-emitting elements and the second light-emitting elements areindividually controllable.
 11. The light-emitting device according toclaim 1, wherein: each of the first light emitting elements comprises: afirst light-emitting diode, a first wavelength conversion memberdisposed on an upper surface of the first light-emitting diode, and afirst protective member that covers lateral sides of the firstlight-emitting diode and lateral sides of the first wavelengthconversion member, and each of the second light emitting elementscomprises: a second light-emitting diode, a second wavelength conversionmember disposed on an upper surface of the second light-emitting diode,and a second protective member that covers lateral sides of the secondlight-emitting diode and lateral sides of the second wavelengthconversion member.
 12. The light-emitting device according to claim 11,wherein the second protective members are separated from the firstprotective members.
 13. The light-emitting device according to claim 1,wherein: each Fresnel lens includes an uneven first surface facing acorresponding one of the light-emitting elements, and a flat secondsurface, such that a light beam emitted from the corresponding one ofthe light-emitting elements is incident on the uneven first surface andis emitted from the flat second surface.
 14. The light-emitting deviceaccording to claim 13, wherein: the uneven first surface of each Fresnellens comprises a plurality of protrusions, at least some of which have asurface that, in a side sectional view, extends diagonally toward therespective one of the light-emitting elements.
 15. A device comprising:the light-emitting device according to claim 1; and a housing comprisinga cover glass that covers the light emitting device, wherein, in theplan view, an outer periphery of the cover glass is positioned inward ofan outer periphery of the compound eye lens.
 16. The device according toclaim 15, wherein: the housing further comprises a main body, the coverglass is located in a through hole of the main body, and in the planview, the compound eye lens overlaps both the cover glass and the mainbody.